Ultra-violet absorption cross sections of isotopically substituted nitrous oxide species: 14N14NO, 15N14NO, 14N15NO and 15N15NO
1Department of Chemistry, University of Copenhagen, Copenhagen, Denmark
2Max-Planck Institute for Nuclear Physics, Atmospheric Physics Division, Heidelberg, Germany
3Air Quality Research Branch, Meteorological Service of Canada, Toronto, Ontario, Canada
4Synchrotron Radiation Research, Lund University, Lund, Sweden
*now at Department of Geosciences, Princeton University, Princeton, New Jersey, USA
Abstract. The isotopically substituted nitrous oxide species 14N14NO, 15N14NO, 14N15NO and 15N15NO were investigated by ultra-violet (UV) absorption spectroscopy. High precision cross sections were obtained for the wavelength range 181 to 218nm at temperatures of 233 and 283K. These data are used to calculate photolytic isotopic fractionation constants as a function of wavelength. The fractionation constants were used in a three-dimensional chemical transport model in order to simulate the actual fractionation of N2O in the stratosphere, and the results were found to be in good agreement with field studies.